There is only one Elvis Presley, but there are also many Elvis Presleys.

No, that’s not an existential riddle about the hip-swiveling, lip-curling singer who irrevocably changed the sound and look of contemporary music, and — with it — popular culture in the 1950s and beyond.

Nor is it a reference to the estimated 35,000 Elvis impersonators still active around the world today, 40 years after the intensely charismatic singer hailed as “The King” permanently left the building on Aug. 16, 1977. He died from a drug-fueled heart attack in Memphis in his famed Graceland mansion, which still draws 600,000 visitors a year (second in the U.S. to the White House).

Only 42, Elvis reportedly weighed 350 pounds at the time of his death — 187 pounds more than when he was 32. He tested positive in his autopsy for 10 different prescription medications, including 10 times his prescribed amount of codeine.

Yet, while he died far too young, Elvis had seemingly lived several lifetimes in just over four decades.

He was a sometimes scorned high school student, an impoverished Memphis truck driver, an aspiring singer, a wealthy pop music superstar, a sergeant in the U.S. Army, a smoldering sex symbol, a movie idol, a middle-of-the-road Las Vegas showroom staple, a bloated, drug-addled victim of fame, and more.

Most significant of all. Elvis was the proto-rock star, an inadvertent revolutionary and a game-changing cultural phenomenon, whose impact extends from The Beatles and U2 singer Bono to Bruno Mars and beyond.

“He is about as iconic as anyone in American music gets,” said John Oates of Hall & Oates.

“When Elvis came on the scene it was like an unbridled and untamed beast had arrived,” said Paul Stanley of Kiss.

“There was a sexuality, a danger and a joy in what he was doing that was the sign of a phenomenon. You see early footage of him, shimmying across the stage and playing for these screaming crowds — he was that generation’s template for everything that came after him and everyone copied that template.”

Indeed, no other solo singing star — not Bing Crosby, Frank Sinatra, Michael Jackson, Madonna or Beyonce — has matched Elvis. His influence and example helped pave the way — directly or indirectly — for The Beatles, Bob Dylan, and countless others.

Presley, seen in 1975, is often referred to as the “King of Rock ‘n’ Roll” or simply “the King.”

Presley, seen in 1975, is often referred to as the “King of Rock ‘n’ Roll” or simply “the King.”

Keystone / Getty Images

“Elvis is my man,” Paul McCartney said. “He was a big influence on the Beatles.”

“There were other American greats, but it was Elvis we talked about,” said former Beatles’ drummer Pete Best. “The effect he had on all the members of The Beatles showed, from our repertoire to the way we played the music and handled ourselves on stage.”

Ringo Starr, who replaced Best in The Beatles, echoed his fellow drummer’s enthusiasm.

“Elvis turned my head around,” Starr said. “Frankie Laine, who I liked (in the early 1950s) was like my dad; everyone you listened to was like your dad, until Elvis came out.”

“I think Elvis changed the dialogue, and maybe the morality, of the entire country. The cultural impact he had can’t be overrated,” Cook said.

“What he managed to do in his career,” Maxwell noted, “was unlike anything ever done before. I know he was very influential to people like Michael Jackson.”

“He was so incredibly unique. He’s definitely somebody to look up to,” said Reinhart, who in March earned a gold record for her understated version of “Can’t Help Falling in Love,” a 1961 hit for Elvis.

Canadian vocal star lang paid tribute to Elvis in a different way. The cover photo for her 2006 album, “Reinternation,” pays homage to the cover photo of him on “Elvis Presley,” his 1956 debut album.

“There’s not too much to not like about Elvis, other than the fact that he was friends with (President) Nixon,” lang said. “Everything he did from the beginning of his career up to his 1968 comeback (TV) special, where he wore the black leather jumpsuit, is pretty untouchable.”

In fact, there was much before Elvis — and many who inspired him profoundly from the worlds of blues, gospel and rhythm-and-blues.

They included a wealth of gifted but obscure African-American musicians and songwriters who created rock ‘n’ roll and paved the way for Elvis and many more.

At a time when much of this country was still segregated, Elvis frequented black nightclubs in Memphis to absorb and study the music of Ike Turner, Jackie Wilson, Little Junior Parker, Matt “Guitar” Murphy and others. The sizzling sensuality of their songs and performances was a major inspiration for him.

Elvis’ first commercially released recording was his reverent 1954 version of bluesman Arthur “Big Boy” Crudup’s “That’s Alright Mama.”

Many of these songs are available in the new 3-CD Sony Legacy box set, “A Boy From Tupelo — The Complete 1953-1955 Recordings.”

Three of Elvis’ landmark early recordings — “All Shook Up,” “Don’t Be Cruel” and “Return to Sender” — were written by Otis Blackwell. Sadly, Blackwell’s own singing career never ignited, despite the fact that Presley’s recordings were almost identical to how Blackwell sang them on his demonstration recordings.

“It’s unfortunate that a lot of songs Elvis was famous for were written by African-American music artists that he didn’t really credit,” said noted New Orleans drummer Herlin Riley. “He changed the whole feeling of rock ‘n’ roll.”

Yet, while Elvis may have been a far more adept musical synthesist than an actual innovator, the power, range and emotional depth of his singing — on stage and on record — were undeniable. Ditto his ability to transcend even so-so songs through the sheer force of his musical skills and personality.

“Elvis was a great, great performer,” said San Diego-born avant garde vocal wizard Diamanda Galas. “Even at the start of his Las Vegas decline, he was phenomenal. It was sad to see a talent like that go away.”

U2’s Bono has at times emulated both the singing and bigger-than-life stage persona of Elvis. U2’s acclaimed 1984 album, “The Unforgettable Fire,” includes “Elvis Presley and America,” a song reportedly inspired by Albert Goldman’s controversial 1981 biography, “Elvis.”

“Even at the height of his middle-of-the-road terror period, at his most hamburger-esque, Elvis could stop the traffic, and not just give them a speeding ticket,” Bono said. “His voice, when he wanted to connect — even in Las Vegas, when he was forgetting the words — that was opera. And it was living opera.”

At first, Elvis’ real-life story was as triumphant as the second act of Verdi’s “Aida.” But, like “Aida’s” harrowing final act, he was destined for doom.

His decline was artistic, physical and spiritual. The superstar who once had it all became a victim of his own success. He also fell prey to forces within and beyond his control, in particular his manager, “Colonel” Tom Parker (in actuality a former Dutch carnival barker born Andreas Cornelis van Kuijk).

Parker turned Elvis into an incredibly lucrative international brand, but at a soul-sapping cost to his once rebellious client. And he funneled an eye-raising amount of Elvis’ earnings to himself.

“Elvis was a tragic figure who should have stood up and fired his manager,” said former Dead Kennedys’ singer Jello Biafra. “The ‘Colonel’ appears to have robbed him blind; it appears Elvis’ handlers preferred him to be strung out on drugs so that he couldn’t take more control of the direction of his career.”

Eagles’ co-founder Don Henley is equally critical of Parker.

“Elvis’ ‘Hound Dog’ was the first rock record I ever owned, so you could say that changed my life completely,” Henley said.

“But Elvis’ manager — rotten son of a bitch that he was — took 50 percent of Elvis’ earnings, which is absolutely disgusting. He put him in all those (crummy) movies, and put him in Vegas. Not that Elvis wasn’t culpable to some degree, but he was just kind of a naive country boy.”

Even as a teenager, though, Elvis was eager to be heard. By so expertly emulating the blues, R&B and gospel music he loved. Elvis had what his first producer, Sun Records’ honcho Sam Phillips, had long sought: “A white man with the Negro sound and the Negro feel.”

It was a potent combination that would change Elvis and — with him — the world, forever.